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Swift is the only U.S. act nominated for top Billboard 200 album for her multiplatinum "Speak Now," which will compete with One Direction's first and second albums — "Up All Night" and "Take Me Home."

They battle it out weekly on the Billboard charts, and now they're competing at the Billboard Music Awards.

Today's biggest stars — from Taylor Swift to fun. to Maroon 5 — are the key finalists at Sunday's awards show, airing live from MGM Grand Garden Arena in Las Vegas on ABC. Those acts are up for 11 awards each; Rihanna, Carly Rae Jepsen and One Direction are up for 10, nine and eight trophies, respectively.

Best of 2013 Billboard Music Awards

Most of the top stars will also blaze the stage, too, including Swift, Justin Bieber, Bruno Mars, Miguel, Macklemore & Ryan Lewis, Chris Brown, Selena Gomez and others.

Prince, who will receive the icon award, will also hit the stage, and Madonna, to be named top touring artist, will make an appearance.

Jepsen, whose nine nominations include top Hot 100 song for the ubiquitous "Call Me Maybe," top female artist and top new artist, will present an award this year.

"The Billboard Awards is kind of a nostalgic one for me because it was the first awards show I attended outside of Canada," the 27-year-old recalled in an interview. "I had never really done anything quite so big. And to be going back a year later, and to be nominated, and then to also being doing all the fun stuff like pick a dress, and see the party, and watch the show — I feel just lucky to be involved."

Jepsen's mentor, Bieber, is up for the night's biggest award, top artist. Other nominees include Swift, Rihanna, One Direction and Maroon 5. Swift is the only U.S. act nominated for top Billboard 200 album for her multiplatinum "Speak Now," which will compete with One Direction's first and second albums — "Up All Night" and "Take Me Home" — Mumford & Sons' "Babel" and Adele's 10 million-selling "21," which won the award last year.

Bieber, Swift and Mars are also up for the fan-voted milestone award.

Comedian-actor Tracy Morgan will host the Billboard Music Awards, which is celebrating its third year back on the scene following a five-year break.

Jepsen, whose new single "Tonight I'm Getting Over You" features Nicki Minaj, said she's excited to see the rapper perform with Lil Wayne on Sunday, but she's also happy to be in her seat and not onstage.

"I can remember being like just a big bundle of nerves last time," she said. "I've had a year of experience under my belt, and I'll probably still be nervous, but I'll be way more excited than anything."